Over the past decade, digital wireless (i.e., cellular) devices have become extremely popular with consumers. As a result, to maintain high customer satisfaction, wireless carriers, manufacturers and certification organizations have expressed interest in establishing higher standards with cellular device verification and certification processes.
To meet the demands of a growing diverse consumer market, carriers offer a wide range of wireless devices, such as cellular phones, personal digital assistants (PDA) and smart phones, from various manufacturers. All of these given device types may operate on the same carrier network simultaneously.
Wireless carriers have been heavily investing in radio frequency auction and infrastructure deployment. To maintain customer satisfaction with respect to voice quality and coverage map without additional infrastructure investment, carriers are striving to obtain high quality mobile wireless devices tested with a unified Radio Frequency (RF) testing standard so that the performance of the wireless devices from different manufacturers can easily be compared and the carriers can verify if these devices meet their network specifications.
It is also desired to have a unified testing standard so that manufacturers can know if the devices they designed can pass the certification of standardization organizations and meet the verification requirements of carriers during the design stage. Standardized testing is critical to the design process because it affects the time to market of the products.
For carriers, manufacturers and certification organizations such as Global Certificates Forum (GCF) and PCS Type Certificates Review Board (PTCRB) schemes, it is desired to have a test method that is reliable, accurate and manageable within a certain time frame. The Cellular Telecommunications & Internet Association (CTIA) has a measurement standard for mobile station over the air performance test plan which is largely adopted by the cellular industry. Two key parameters to determine wireless mobile station transmit and receive capabilities are total radiated power (TRP) and total isotropic sensitivity (TIS). TRP is a combined number of the average transmit antenna gain and transmit power, which determines the uplink performance of the terminal. The TIS is a single figure of merit that quantifies the mobile station's capability of receiving a weak signal averaged over a sphere.
Within the standard, the TRP measurement process is relatively fast and accurate compared to the TIS method. Yet, downlink and uplink performance are of equal importance. Poor TIS can result in a low quality voice signal, and it can also alter coverage maps. The current TIS test methodology suffers from the problems of lost base station signals (i.e., termination of calls), relatively large measurement uncertainty and relatively long test times as compared to the TRP test methodology.